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請原諒我,如果我的問題不專業。我正在閱讀IBM的x10教程。下面是計算PI,但讓我困惑的代碼:X10並行處理共享變量
public static def countPoints(n: Int, rand:()=>Double) {
var inCircle: Double = 0.0;
for (var j:Long = 1; j<=n; j++) {
val x = rand();
val y = rand();
if (x*x +y*y <= 1.0) inCircle++;
}
return inCircle;
}
val N = args.size() > 0 ? Long.parse(args(0)) : 100000;
val THREADS = args.size() > 1 ? Int.parse(args(1)) : 4;
val nPerThread = N/THREADS;
val inCircle = new Array[Long](1..THREADS);
finish for(var k: Int =1; k<=THREADS; k++) {
val r = new Random(k*k + k + 1);
val rand =() => r.nextDouble();
val kk = k;
async inCircle(kk) = countPoints(nPerThread,rand);
}
var totalInCircle: Long = 0;
for(var k: Int =1; k<=THREADS; k++) {
totalInCircle += inCircle(k);
}
val pi = (4.0*totalInCircle)/N;
程序本身並不難,我的問題是,因爲每個countPoints()調用它重複調用參數蘭特,之前產卵多線程,只一個蘭特被創建,不同的線程將共享相同的蘭特並引發競爭狀態?如果不是,爲什麼?